1. Field of the Invention
The present invention relates generally to electrical apparatus for making random selections and more particularly to apparatus for making at random one selection on the average in every "N" cases where "N" is an integer having a value greater than one.
2. Discussion of Background
Systems for making random selections are useful in a very wide variety of activities, from games of chance to quality control to security applications, where one token or manufactured item or person on the average out of some number of items is randomly selected. In secure facilities, employees and visitors, selected at random, may be subjected to searches or contraband. It is important that security not be defeated by those seeking to avoid being searched and that inspections of manufactured items be sufficiently random so that a true picture of product quality is presented.
A number of devices exist for generating random numbers or random selections. Many of these are computer-based and some use pseudorandom numbers in making selections. See as examples, the apparatus disclosed by Malady, et al. in U.S. Pat. No. 4,811,247, by Bennison in U.S. Pat. No. 4,580,226 and by Bishop in U.S. Pat. No. 3,961,169. Malady employs a decade counter, a dual 4-bit register, two 16:1 multiplexers and a dual BCD counter to make select/non-select determinations. Bennison stores pseudorandom numbers in a large computer memory. Bishop generates pseudorandom numbers by AND-gating a random series of "1's" and "0's" against a series of clock pulses.
In another approach, Simkus, et al., as described in U.S. Pat. No. 4,819,818, uses counters to cycle quickly through a count, stopping at some number in the range during one of the cycles, to simulate the roll of dice. If two dice are simulated, one counter is stopped on the pressing of a "roll" button and the other counter is stopped on the release of the button.
Many of these devices are unduly complicated, expensive and are unsuitable for environments which are not climate controlled, such as the floor of a manufacturing facility or the entrance to a secure facility. There is a need for a simple, rugged apparatus for selecting, at random and on average, one item out of every N items.